If you're considering growing a small clethra (Clethra alnifolia) in an outdoor plant box, the answer is yes—with the right conditions. Clethra, also known as summersweet, thrives in moist, well-drained soil and partial to full shade, making it a versatile choice for container gardening.

When selecting an outdoor plant box, ensure it’s large enough to accommodate the plant’s root system, ideally at least 18 inches deep and wide. Use high-quality potting mix enriched with organic matter to retain moisture, as clethra prefers consistently damp soil. Regular watering is crucial, especially during hot summers, to prevent the soil from drying out.

Additionally, place the plant box in a shaded or partially shaded area to mimic the clethra’s natural habitat. With proper care, your small clethra can flourish in an outdoor plant box, adding fragrant blooms and lush foliage to your patio or balcony garden.